Authorities said a thin strip of plastic is actually comparable to water because, if it was struck at close range the damage would be minimal. Deputy Ross said going highway speeds and striking the plastic could be disastrous.

"Could be absolutely fatal," he said, "absolutely."

The Idaho Transportation Department personnel caught the suspects in the act Sunday night, but the suspects took off on foot and got into a vehicle before law enforcement arrived.

Authorities have little information on the suspects other than they were wearing dark clothing and had flashlights.

"It's warming up, people are starting to ride their bikes again," Ross said.

"That could be a serious, serious issue."

Deputies said that if someone were to be killed by these actions, it would mean manslaughter charges.